Electric actuator for a marine vessel

Patent metadata

Field	Value
Publication number	US-10940927-B2
Application number	US-201815978788-A
Country	US
Kind code	B2
Filing date	May 14, 2018
Priority date	May 14, 2018
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

An actuator for imparting steering movement to a tiller of a propulsion unit of a marine vessel comprises an absolute position sensor which senses a steering position and a relative position sensor which senses a position of the motor. A steering control unit calibrates the relative position sensor based on a signal of the absolute position sensor. Calibration of the relative position sensor based on a signal of the absolute position sensor initializes an accumulative position which accumulates a relative position as the actuator moves over time.

First claim

What is claimed is:

1. An actuator for imparting steering movement to a tiller of a propulsion unit of a marine vessel, the actuator comprising:
a housing;
an output shaft received by the housing, the housing linearly reciprocateable relative to the output shaft;
a motor disposed within the housing, the motor having a rotor and a stator, the rotor operable to have a magnetic field and the stator operable to have a magnetic field, rotation of the rotor causing the rotor to translate axially relative to the output shaft and causing the housing to reciprocate linearly relative to the output shaft;
a relative position sensor operable to sense a position of the rotor; and
a steering control unit operable to energize the stator to align the magnetic field of the stator with the magnetic field of the rotor based on the position of the rotor sensed by the relative position sensor to hold the position of the rotor;
wherein the actuator is coupled to the tiller of the marine vessel such that linear movement of the housing relative to the output shaft imparts a steering force to the tiller of the marine vessel.

2. The actuator as claimed in claim 1 , further comprising:
an absolute position sensor operable to sense a steering position;
wherein the steering control unit is further operable to calibrate the relative position sensor based on a signal of the absolute position sensor, wherein calibration of the relative position sensor based on the signal of the absolute position sensor initializes an accumulative position which accumulates a relative position as the actuator moves over time.

3. The actuator as claimed in claim 2 , wherein the steering control unit a is further operable to compare the signal of the absolute position sensor and the accumulative position for fault detection.

4. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to initialize the accumulative position of the relative position sensor with the absolute position sensor when the actuator is started-up.

5. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to monitor the accumulative position and the steering position during a change in steering direction to determine backlash.

6. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to monitor backlash during initial steering movement and to compensate for backlash by reinitializing the accumulative position.

7. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to restrict a steering range of the actuator after initialization of the accumulative position and before compensating for backlash.

8. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to use the accumulative position for position control of the actuator.

9. The actuator as claimed in claim 2 , wherein the steering control unit is further operable to use a redundant sensor for position control of the actuator if the absolute position sensor or the relative position sensor fails.

10. The actuator as claimed in claim 1 , wherein the motor is at least a two-phase motor and the steering control unit is further operable to energize the stator by applying a PWM to at least one phase of the motor to generate a magnetic field that aligns with and holds the position of the rotor.

11. The actuator as claimed in claim 10 , wherein the steering control unit is further operable to apply a minimum PWM to create a holding torque which counters a back driving torque.

12. The actuator as claimed in claim 11 , wherein the steering control unit is further operable to determine the minimum PWM as a function of marine vessel speed, engine RPM, steering position, or two or more thereof.

13. The actuator as claimed in claim 11 , wherein the steering control unit is further operable to increase or decrease the minimum PWM applied in order to counter the back driving torque.

14. The actuator as claimed in claim 13 , wherein the steering control unit is further operable to determine a magnitude and rate of PWM increase based on a signal from a position sensor sensing back driving.

15. The actuator as claimed in claim 13 , wherein the steering control unit is further operable to determine a magnitude and rate of PWM increase based on a signal from a torque sensor sensing back driving torque.

16. The actuator as claimed in claim 1 , further comprising a joint coupling the housing to the tiller of the marine vessel.

17. The actuator as claimed in claim 16 , wherein the joint is a ball joint.

18. A marine steering system comprising:
the actuator as claimed in claim 1 ;
a power source operable to supply electric power to the motor; and
a sensor operable to sense a capacity of the power source;
wherein the steering control unit is further operable to limit the maximum electric power supplied to the motor by controlling the voltage to the motor relative to the capacity of the power source.

19. The actuator as claimed in claim 18 wherein the steering control unit is further operable to limit the maximum electric power supplied to the motor by increasing or decreasing PWM based on whether the battery current is in a first zone, a second zone, or a third zone.

20. The actuator as claimed in claim 19 wherein the steering control unit decreases PWM when the battery current is in the first zone.

21. The actuator as claimed in claim 19 wherein the steering control unit increases or decreases PWM when the battery current is in the second zone.

22. The actuator as claimed in claim 19 wherein the steering control unit prevents increasing PWM when the battery current is in the third zone.

23. A marine steering system comprising:
a first propulsion unit having a tiller, an actuator operable to impart steering movement to the tiller of the first propulsion unit, and a position sensor operable to sense a steering position of the first propulsion unit, the actuator of the first propulsion unit comprising:
a housing;
an output shaft received by the housing, the housing linearly reciprocateable relative to the output shaft;
a motor disposed within the housing, the motor having a rotor and a stator, the rotor operable to have a magnetic field and the stator operable to have a magnetic field, rotation of the rotor causing the rotor to translate axially relative to the output shaft and causing the housing to reciprocate linearly relative to the output shaft;
a relative position sensor operable to sense a position of the rotor; and
a steering control unit operable to energize the stator to align the magnetic field of the stator with the magnetic field of the rotor based on the position of the rotor sensed by the relative position sensor to hold the position of the rotor;
wherein the actuator is coupled to the tiller of the first propulsion unit such that linear movement of the housing relative to the output shaft imparts a steering force to the tiller of the first propulsion unit; and

a second propulsion unit having a tiller and an actuator operable to impart steering movement to the tiller of the second propulsion unit, and a position sensor operable to sense a steering position of the second propulsion unit;
wherein the steering control unit is further operable to impart steering movement to the first propulsion unit based on relative steering positions of the first propulsion unit and the second propulsion unit, wherein

Assignees

• Marine Canada Acquisition Inc
• Marine Canada Acquistion Inc

Inventors

• Chan Anson Chin Pang
• Carlson Ian Michael
• Wong Ray Tat Lung
• Dyck Mark Isaac

Classifications

• B62D5/0427

  the axes being coaxial · CPC title

• B63H20/12 Primary

  Means enabling steering · CPC title

• G05D1/0206

  specially adapted to water vehicles · CPC title